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The 991.2Cups used the new DFI engines which have the distinct advantage of higher weight and lower CG. Long term durability is still a bit of a question mark on the DFI engines and they can supposedly only be rebuilt twice before being scrapped as they don't use replaceable liners in the case. The Mezger was used on the 991.1Cups through 2016. Basically Porsche knew the Mezger was a better engine for racing than what they put in the 991GT street cars during those years. It appears they did not have faith in the early DFI motors The overhaul interval is same on the 991Cup Mezgers as on the 997Cups and listed as 50hrs. The engines can safely go to 150hrs or more and evidently still look great when opened up. Even most race teams go to 100hrs on these generally. My bet is that this engine will be like new inside besides some bearing wear. We are going to be replacing the pistons/liners, rods, and all bearings anyway. If we go with a 4.3 build than the RSR 80.1mm crank will be swapped in place of the 76.4mm Cup crank otherwise it stays.
This engine was pulled by an Aussie race team from one of their cars and swapped out for a fresh new PM crate motor. As such it was available for purchase. It was exactly what I was looking for since it has the latest dual oil squirter German made Motorsport case along will all the latest parts like those were are already using in my current engine. Using a 996TT or 997TT engine for a build would not make sense as virtually none of the main parts could be used.
Makes all the cars listed for 40/50hrs needing service seem like excellent deals for someone just considering weekend track days. I always thought the service intervals were extreme. GL with it.
Manthey makes a 4.4 liter I think and Mirage Int'l has their own 4.4l based Mezger, but it's big $$$
The 4.4L Manthey was a normally aspirated engine built using a custom Manthey stroker crankshaft. You could not do this with a turbocharged application. I don't believe they still make the 4.4.
Makes all the cars listed for 40/50hrs needing service seem like excellent deals for someone just considering weekend track days. I always thought the service intervals were extreme. GL with it.
The 991 sequential gearbox has a 40hr overhaul interval. Based on what I'm hearing, guys are opening up the gearbox at twice the hours and everything is fine so they simply button it up and keep going. Same with the engines especially for the weekend racers. If you are an unlimited budget Pro team setting the car up for a 24hr endurance races, that's a different story. Nobody I"m aware of is overhauling these things at 40-50hrs. 100hrs seems to be the minimum
Last edited by powdrhound; 04-19-2024 at 01:06 PM.
Manthey makes a 4.4 liter I think and Mirage Int'l has their own 4.4l based Mezger, but it's big $$$
Originally Posted by powdrhound
The 4.4L Manthey was a normally aspirated engine built using a custom Manthey stroker crankshaft. You could not do this with a turbocharged application. I don't believe they still make the 4.4.
Awhile ago, a GT3RS came up for sale with a Manthey4.4 in it, attached dyno sheets showed 565/70 hp to the wheels, and I could only imagine how much fun that would have been to drive, let alone how it must sound.
Just got some pics from the shop on the progress of the new 3.5" Y-pipe which was drawn up in CAD last week. It's getting mocked up to make sure it's a direct bolt in and fit with the OEM airbox. This particular version is going to have a single larger Tial diverter valve in the center of the collector ahead of the throttle body in place of the dual OEM valves / F-hose. This will greatly open up the area on the left side the engine. The single diverter will recirculate into the intake manifold just like OEM. We anticipate this larger Y-pipe with significantly open up flow in the intake side.
Maybe I missed it in my scrolling but what happened to this Y-pipe setup with the stock air box? Doesn't look like you are running it?
Any heat issues now that air is not flowing under the engine?
Originally Posted by powdrhound
I"ve been meaning to do this for a long time but just got around to installing the 997GT3/Cup flat underbody paneling. The panels use the existing attachment points in the center but naturally the attachment points are different around the perimeter since the 996 chassis doesn't have any panels there. You will simply need to install 10 riv-nuts to bolt every thing up at correct locations at the outboard points. I used M5 riv-nuts with M5x16mm flanged bolts. With a lift this is a very easy job for anyone who is moderately handy and knows how to use a rig-nut tool. Sheet metal screws in place of bolts can be used but that's a little more ghetto and not quite as durable long term. This mod can be done to any 996 chassis.
This mod significantly smooths out the airflow under the car. We are in the process of developing strakes for the underside like those used on the later 991 and 992 race cars and also a diffuser which will tie in with the aft-most panel covering the underside of the engine and extending out to the rear bumper.
That is an incredibly simple answer to a very stupid question. I’m ashamed I even asked it.
Not a stupid question. Look at how an aircooled engine works/is cooled. Air is pulled from the fan, through shrouds, and through the cylinders at the ground. Having it blocked off is not an unreasonable question.
04-19-2024 | 12:57 PM
